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Gonadal development during the lifetime of the fastest maturing model vertebrate- turquoise killifish (Nothobrachius furzerí)
LANDOVÁ, Magdaléna
Turquoise killifish had to adapt to the inhospitable conditions in which they live, especially drying temporal water bodies, which means certain death. The life sprint of the representatives of this genus is at its peak within one-month post-hatching, when both sexes have fully developed gonads and can reproduce. This rate comes with a high cost, as the killifish gonads begin to show signs of tissue degradation and germ cell apoptosis as early as three months post-hatching. Germ cell loss increases with age. A description of the development and degradation of the gonads in males and their breeding was elaborated. For the evaluation of aging-specific changes, immunochemical methods were used, focusing on the binding of specific antibodies against target epitopes and their visualization using fluorescence microscopy. Procedures for histological specimens have also been described, both for classical light and fluorescence microscopy.
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Meiosis and fertility of juvenile mouse males
Valtrová, Pavlína ; Trachtulec, Zdeněk (advisor) ; Reifová, Radka (referee)
This work is a summary of literature on pecularities of spermatogenesis in juvenile mouse males (Mus musculus) and their utilization. Spermatogenesis is a process that leads through meiosis to sperm production. The cell undergoes in waves the following cell types: spermatogonia, spermatocytes, spermatids, and spermatozoa. Juvenile mice (whose testes size and sperm count have not reached their maximum) are often used to study individual cell types. The transition between cell types takes shorter time in juveniles. Spermatozoa from the 1st wave of spermatogenesis (WS) are derived from prenatal gonocytes, allowing earlier sperm production. They have a lower frequency of crossing over (CO rate) due to a different processing of CO intermediates; the consequence can be aneuploidy (one chromosome less/more). Spermatozoa from the 2nd WS still display lower CO rate. In 3rd WS testes descend and their temperature decreases to 33řC; CO rate is more like in adults. In 4th WS is typical testicular supportive cells mature and CO rate is similar to adult levels. Juvenile males also suffer from more frequent and severe sperm malformations. Low CO rate should not have an impact on fertility; errors are eliminated during meiotic checkpoints. However, the children of young fathers have a higher risk of aneuploidy,...
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